This invention relates to pneumatically powered hand-held torque wrenches having means for measuring and displaying the amount of torque applied to a fastener.
The structure and operational characteristics of the wrench per se are known in the art, for example, as disclosed in U.S. Pat. No. 3,621,738, granted to O. V. Northcutt on Nov. 23, 1971. This invention concerns the addition of a torque measuring and display means on a wrench of the type disclosed in said patent.
A feature of the invention resides in the fact that after a fastener setting operation, the torque reading will be maintained until reset by the operator.
Another feature of the invention is that the tool operator can see the value of torque as it is being developed during tool operation.
Still another feature is that the torque developed by the tool can be measured in a forward as well as a reverse direction, and with or without pressurized medium being supplied to the tool.
Another feature of the tool of the invention is use of a simple torque tube to provide resistance force to tool handle flexure, which torque tube also serves as a pressure medium conduit for the tool motor.
A further feature of the tool is simplicity in structural detail and operational characteristics, as well as a tool which will provide accurate torque read-out and long, trouble-free service.
Other features and advantages of the invention over known prior art devices, will be evident from the invention disclosure which follows: